Perhaps you should try some spelling variations:
astronomy surveys » astronomy survey, astronomy surveying, astronomy survives
astronomy sergey » astronomy survey, astronomy seven, astronomy large
c practical » 2 practical, 7 practical, 8 practical
patrick c » patrick _, patrick a, patrick d

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: the patrick c practical ((astronomy surveys) OR (astronomy sergey)).
• Adding a wildcard symbol may retrieve word variants: the patrick c practical ((astronomy surveys) or (astronomy sergey))*.